Robotic transport devices for transporting small components are technical devices for transporting and storing bulk material. They are e.g. required in automated manufacturing plants and assembly operations, amongst others in the electronic, automobile and packaging industry. They are also referred to as supply robots or transport robots. In this context, small components may not only have very different shapes and materials, but also have a large variety of dimensions. Most components are in the millimeter range, however, the small components may also be smaller or larger than that.
Originally, this kind of transport was carried out by crane-like robotic transport devices. These simulate all but manual labor picking up an electronic component from a surface and carrying it to a different location where it is stored for further processing. An automatic transport device e.g. implements this by a robot arm which picks up the electronic component by a gripper and places it at the desired location.
In this context, it may be problematic that not every electronic component to be transported can be found at the same starting location. It is true that for preparing the transport, the electronic components are frequently spread out onto a surface so that an electronic component may respectively be gripped; however, due to the spreading out on the surface each individual electronic component is then located at a slightly different location which may in x and y direction differ slightly from the ideal location for gripping or, respectively, receiving.
In practice, so-called vibrating spiral feed bowls or a flexible component conveying surface combined with an image-processing system and an industrial robot are frequently used. In this context, the small components to be transported are at first singularized in an unsorted manner on a horizontal surface, detected by the visual component-detection system or, respectively, the image-processing system and eventually picked up by the industrial robot. The singularized small components are subsequently transported via a predetermined distance, placed at the target location and forwarded for further processing. An example for such a construction is e.g. disclosed in EP 916 457 A2 or, respectively, in U.S. Pat. No. 6,056,108 A.
An essential disadvantage of conventional concepts is that due to the separate handling of the individual small components and the comparatively long travelling paths of the robot arm between gripping the component on the receiving surface and releasing the component at the location of feed, the cycle time is relatively high which may render the procedure carried out annoyingly slow. Existing robot-based supply systems are thus flexible in use when compared to vibrating spiral feed bowls, but relatively slow. The object is thus to carry out measures relating to robot geometry. This is cost-intensive and furthermore limits other possibilities.
Other types of transport of similar small components provide a transport mechanism with linear movements as e.g. described U.S. Pat. No. 6,688,451 B2. Instead of a flexible robot arm, a construction remotely reminiscent of a cable car is used forming an oblong oval. An endless haul track or chain forming the oval itself is placed around two deflection pulleys at the end of the oval, the deflection pulleys also serving as drive discs. By this haul track, grippers are guided that grip the electronic components at the receiving location and store them at the target or storing location in a predetermined manner, the path from the receiving location to the target or storing location being formed by one of the two longitudinal sides of the oval while the other longitudinal side of the transport mechanism is used to return the gripper for re-use.
At this point, the problem occurs that the receiving location and the storing location have to be found very accurately so that the gripping elements may each grip and release the small components at the corresponding locations.
This problem has already been recognized. U.S. Pat. No. 7,712,598 B1 proposes to configure the individual gripping devices in a moveable manner so that the receiving and release procedures may be carried out in a more varied manner. In this context, it is furthermore described that such a transport system may also be suspended at a SCARA robot arm. Such a technical concept, however, is not precise enough for many applications. A further problem is that they describe technical concept requires special components and may not be put into practice by standard components of automation that are freely available and thus inexpensive.
A demand still exists for robotic transport devices for small components that comprise even more possibilities and may fulfill certain aspects of the occurring problems in a better and more flexible manner than the already known robotic transport devices.
Accordingly, a demand exists for methods for carrying out such transports.